An electro-mechanical connector of the kind with which we are particularly concerned here, includes plug and mating receptacle parts which can be releasably joined to interconnect through internally located contacts, a set of cables or harness wires brought to each of the connector parts. Such electrical connectors have a wide use in providing releasable connections for electrical and electronic equipment of great variety.
Such equipment, especially electronics equipment, is especially susceptible to disturbance and even damage from external interference electromagnetic fields. The external electromagnetic interference can be of a relatively low level which induces noise into electronic circuits and cabling, and is detrimental to operational efficiency and accuracy. Still higher levels of interference fields such as radar, for example, can result in substantial disruption of operation of electronics equipment if precautions are not taken. For very high levels of interference, such as that which can occur at a substantial distance from a nuclear occurrence for example, and which can induce currents in the range of hundreds or perhaps thousands of amperes, sensitive, unshielded electronic equipment can be completely damaged or destroyed. Higher level interference of this latter kind is frequently referred to as electromagnetic pulse or EMP interference.
Cabling to electrical and electronic equipment that it is desired to protect against external interference fields is typically enclosed within a metal braid or other conductive shield extending from an equipment termination point and to termination at a releasable connector. It is this termination at a connector with which we are particularly concerned here.
At the present time, termination of a cable shield to an electrical connector is conventionally accomplished by the use of jumpers, pigtails or daisy chains which conductively interconnect the cable shield at a point closely adjacent to the connector and the connector shell. Despite their wide present use, they do not provide fully satisfactory termination in that substantial "windows" are available for the polluting fields to make their way to the cable wires or to internal parts of the electrical connector.
There are other situations in which there is a similar need for termination of shielded cable wires. For example, there is a class of terminal junction blocks which consist generally of a metal housing enclosing contacts each which is accessible through an opening in a wall of the housing. Shielded cable wires having complementary contacts on their ends are each inserted through the junction block housing opening and mated with an enclosed contact. Termination of the cable wire shield has in the past been accomplished as discussed above in connection with electromechanical connectors.